Across Interfacial Li + Conduction Accelerated by a Single-Ion Conducting Polymer in Ceramic-Rich Composite Electrolytes for Solid-State Batteries.

Composite electrolytes have been accepted as the most promising species for solid-state batteries, exhibiting the synergistic advantages of solid polymer electrolytes (SPEs) and solid ceramic electrolytes (SCEs). Unfortunately, the interrupted Li + conduction across the SPE and SCE interface hinders the ionic conductivity improvement of composite electrolytes. In our study on a ceramic-rich composite electrolyte (CRCE) membrane composed of borate polyanion-based lithiated poly(vinyl formal) (LiPVFM) and Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) particles, it is found that the strong interaction between the polyanions in LiPVFM and LATP particles results in a uniform distribution of ceramic particles at a high proportion of 50 wt % and good robustness of the electrolyte membrane with a Young's modulus of 9.20 GPa. More importantly, ab initio molecular dynamics simulation and experimental results demonstrate that Li + conduction across the SPE and SCE interface is induced by the polyanion-based polymer due to its high lithium-ion transference number and similar Li + diffusion coefficient with the SCE. Therefore, the unblocked Li + conduction among ceramic particles dominates in the CRCE membrane with a high ionic conductivity of 6.60 × 10 -4 S cm -1 at 25 °C, a lithium-ion transference number of 0.84, and a wide electrochemical stable window of 5.0 V (vs Li/Li + ). Consequently, the high nickel ternary cathode LiNi 0.8 Mn 0.1 Co 0.1 O 2 -based batteries with CRCE deliver a high-rate capability of 135.08 mAh g -1 at 1.0 C and a prolonged cycle life of 100 cycles at 0.2 C between 3.0 and 4.3 V. The polyanion-induced Li + conduction across the interface sheds new light on solving composite electrolyte problems for solid-state batteries.